Developmental coordination disorder pertains to a deficit in perceptuo-motor synchronization independent of attentional capacities

We investigated from a dynamic pattern perspective to motor coordination whether the deficiency in motor coordination characterizing Developmental Coordination Disorder children pertains to a general disorder in synchronization leading to a lower stability of the performed coordination pattern, and the extent to which the trouble is linked to attentional capacities. Twenty-four DCD children without ADHD aged eight to thirteen and 60 control children were asked (1) to perform a Continuous Performance Test assessing sustained attention; (2) to flex one finger either in synchrony or in syncopation with a visual periodic signal whose frequency was increased stepwise, assessing synchronization abilities. For the attentional task, percentage of exact responses, number of errors and reaction time were recorded. For the synchronization task, we measured relative phase (i.e., the ratio between the stimulus and the response onset and the time separating two successive stimuli). DCD children were significantly more variable than controls in both conditions and the difficulty in synchronization was unrelated to attentional disorders (ANCOVA). These findings support the idea of a general synchronization disorder in DCD children underlying their poor motor coordination. Moreover, this synchronization disorder does not appear to be strictly dependent on the level of sustained attentional capacities.     

Pointing with the left and right hands in congenitally blind children

Congenitally blind and blindfolded sighted children at ages of 6, 8, 10 and 12 years performed a pointing task with their left and right index fingers at an array of three targets on a touch screen to immediate (0 s) and delayed (4 s) instructions. Accuracy was greater for immediate than delayed pointing and there was an effect of delay for the orientation of the main axis of the pointing distribution in both groups, indicating distinct spatial representations with development such as ego- and allocentric frames of reference, respectively. The pointing responses of the blind covered less surface area indicating better overall accuracy as compared to the sighted blindfolded. The hands differed for four of the six precision and accuracy parameters. The right hand performed better and seemed relatively contextually oriented, whereas the responses of the left hand were closer to the body and egocentrically oriented. The elongation of the scatter of the pointing responses was greater for the boys and more allocentrically oriented, indicating gender differences in spatial representation. The study provides a first evidence of ego- and allocentric spatial frames of reference in congenitally blind children and an ability to point at targets with the left and right hands in the total absence of vision.     

Reproducibility of distance and direction errors associated with forward, backward, and sideway walking in the context of blind navigation

The ability to navigate without vision towards a previously seen target has been extensively studied, but its reliability over time has yet to be established. Our aims were to determine distance and direction errors made during blind navigation across four different directions involving three different gait patterns (stepping forward, stepping sideway, and stepping backward), and to establish the test-retest reproducibility of these errors. Twenty young healthy adults participated in two testing sessions separated by 7 days. They were shown targets located, respectively, 8 m ahead, 8 m behind, and 8 m to their right and left. With vision occluded by opaque goggles, they walked forward (target ahead), backward (target behind), and sideway (right and left targets) until they perceived to be on the target. Subjects were not provided with feedback about their performance. Walked distance, angular deviation, and body rotation were measured. The mean estimated distance error was similar across the four walking directions and ranged from 16 to 80 cm with respect to the 8 m target. In contrast, direction errors were significantly larger during sideway navigation (walking in the frontal plane: leftward, 10 degrees +/- 15 degrees deviation; rightward, 18 degrees +/- 13 degrees) than during forward and backward navigation (walking in the sagittal plane). In general, distance and direction errors were only moderately reproducible between the two sessions [intraclass correlation coefficients (ICCs) ranging from 0.682 to 0.705]. Among the four directions, rightward navigation showed the best reproducibility with ICCs ranging from 0.607 to 0.726, and backward navigation had the worst reliability with ICCs ranging from 0.094 to 0.554. These findings indicate that errors associated with blind navigation across different walking directions and involving different gait patterns are only moderately to poorly reproducible on repeated testing, especially for walking backward. The biomechanical constraints and increased cognitive loading imposed by changing the walking pattern to backward stepping may underlie the poor performance in this direction.     

Close to me: multisensory space representations for action and pre-reflexive consciousness of oneself-in-the-world

Philosophical considerations as well as several recent studies from neurophysiology, neuropsychology, and psychophysics converged in showing that the peripersonal space (i.e. closely surrounding the body-parts) is structured in a body-centred manner and represented through integrated sensory inputs. Multisensory representations may deserve the function of coding peripersonal space for avoiding or interacting with objects. Neuropsychological evidence is reviewed for dynamic interactions between space representations and action execution, as revealed by the behavioural effects that the use of a tool, as a physical extension of the reachable space, produces on visual-tactile extinction. In particular, tool-use transiently modifies action space representation in a functionally effective way. The possibility is discussed that the investigation of multisensory space representations for action provides an empirical way to consider in its specificity pre-reflexive self-consciousness by considering the intertwining of self-relatedness and object-directness of spatial experience shaped by multisensory and sensorimotor integrations.     

Maternal odor shapes rapid face categorization in the infant brain

To successfully interact with a rich and ambiguous visual environment, the human brain learns to differentiate visual stimuli and to produce the same response to subsets of these stimuli despite their physical difference. Although this visual categorization function is traditionally investigated from a unisensory perspective, its early development is inherently constrained by multisensory inputs. In particular, an early‐maturing sensory system such as olfaction is ideally suited to support the immature visual system in infancy by providing stability and familiarity to a rapidly changing visual environment. Here, we test the hypothesis that rapid visual categorization of salient visual signals for the young infant brain, human faces, is shaped by another highly relevant human‐related input from the olfactory system, the mother's body odor. We observe that a right‐hemispheric neural signature of single‐glance face categorization from natural images is significantly enhanced in the maternal versus a control odor context in individual 4‐month‐old infant brains. A lack of difference between odor conditions for the common brain response elicited by both face and non‐face images rules out a mere enhancement of arousal or visual attention in the maternal odor context. These observations show that face‐selective neural activity in infancy is mediated by the presence of a (maternal) body odor, providing strong support for multisensory inputs driving category acquisition in the developing human brain and having important implications for our understanding of human perceptual development.     

Insensitivity of visual short-term memory to irrelevant visual information

Several authors have hypothesized that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996b). Experiment 1 replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery.     

The Use of the Term Virtual Reality in Post-Stroke Rehabilitation: A Scoping Review and Commentary

Virtual reality (VR) offers many opportunities for post-stroke rehabilitation. However, “VR” can refer to several types of computer-based rehabilitation systems. Since these systems may impact the feasibility and the efficacy of VR interventions, consistent terminology is important. In this study, we aimed to optimize the terminology for VR-based post-stroke rehabilitation by assessing whether and how review papers on this topic defined VR and what types of mixed reality systems were discussed. In addition, this review can inspire the use of consistent terminology for other researchers working with VR. We assessed the use of the term VR in review papers on post-stroke rehabilitation extracted from Scopus, Web of Science and PubMed. We also developed a taxonomy distinguishing 16 mixed reality systems based on three factors: immersive versus semi-immersive displays, the way in which real and virtual information is mixed, and the main input device. 64% of the included review papers (N = 121) explicitly defined VR and 33% of them described different subtypes of VR, with immersive and non-immersive VR as the most common distinction. The most frequently discussed input devices were motion-capture cameras and handheld devices, while regular 2D monitors were the most frequently mentioned output devices. Our analysis revealed that reviews on post-stroke VR rehabilitation did not or only broadly defined “VR” and did not focus on a specific system. Since the efficacy and feasibility of rehabilitation may depend on the specific system, we propose a new data-driven taxonomy to distinguish different systems, which is expected to facilitate communication amongst researchers and clinicians working with virtual reality.     

Deficit in phonological processes: a characteristic of the neuropsychological profile of children with NF1

Learning disabilities are one of the most frequent complications of neurofibromatosis type 1 (NF1) in children. Studies of the effects of the neurocognitive deficit on academic performance are relatively rare, owing to the small size of the populations concerned. However, research is needed to develop effective rehabilitation programs. In the present study, we explored the impact of a possible phonological deficit on the reading abilities of children with NF1. A multicenter, cross-sectional study was conducted in France on two groups of 75 children with or without NF1 aged 8–12 years, matched for age, sex, handedness, and reading level. All participants underwent a neuropsychological evaluation to assess their general cognitive level, reading skills, phonological processes, visuoperceptual abilities, and attentional capacity. Phonological skills were assessed by means of two phonological awareness tasks and one short-term memory task. In the group of children with NF1, 41% had reading difficulties. Phonological processes were impaired in this group, compared with the children without NF1. Similar differences were found for a phoneme deletion task after adjustment for reading difficulties, IQ level, and visuoperceptual abilities. Phonological awareness, but not phonological short-term memory, was impaired in children with NF1, and not just those whose reading was impaired. Results suggest that children with NF1 have a phonological awareness deficit, whatever their reading level. Identification of reduced phonological skills may warrant the implementation of a specific rehabilitation program before early reading difficulties emerge.     

Stimulus congruence and stimulus-response compatibility: Two variables disentangled in an auditory reaction time task

Abstract

Stimulus—response (S-R) compatibility was a tem fmt used by Wtts and Seeger (1953) to describe effcts observed on reaction time (RT) when the stimulus—response relationship was varied, as in the following instructions: “move to tbe right when the stimulus appears on the right” (compatible) or “move to the left when the stimulus appears on the right” (incompatible). This term was later employed in a broader sense (Simon & Rudell, 1967) with paradigms involving elaborate stimuli, such as the verbal command ‘RIGHT’ delivered to the right tar (compatible) or to the left ear (incompatible). In such paradigms. subjects respond faster when the response is delivered on the same side as the stimulus (the so-called “Simon effect”). It has been shown, however, that this effect could be reversed under some circumstanas in the visual domain. In this paper, we report data showing that it can also be reversed in the auditory domain when using the above-mentioned verbal commands. This brings further evidence that stimulus-response compatibility and the Simon effect difier in essence, with the latter effect reflecting the influence of stimulus congruence, the correspondence relationship borne by the two simultaneous characteristics of the stimulus. Stimulus congruence and stimulus-response compatibility had indeed independent influences on RT, which in a serially connected information-processing modcl would imply that they act upon independent stages.